According to the Brewers' PR staff, it's the first time in 24 years that the Brewers have been alone on the cover of SI (that would be the Rob Deer cover of 1987).
Over the month of August, the Brewers have slowly gotten themselves more mainstream attention. SI isn't what it used to be, but it's still hard to get more mainstream than that cover. Over the past couple weeks, we've even seen ESPN take up a few "Are the Phillies REALLY the favorites in the NL? What about the Brewers?" debates.
They'll cool down eventually, but being in the national spotlight is almost never a bad thing. The only downside is that those of us who have been along for the ride for the past few seasons are starting to feel like kids who liked a band before the big hit single came along.